Wave signal tuner



Nov. 19, 1957 A. J. CLARK ET AL WAVE SIGNAL TUNER Filed July 17, 1956 RF NA. 05g', l F' A F' AMR*- Df'no- AM@ AMP 2 /l /l/ .Z512

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WAVE SIGNAL TUNER Alfred J. Clark, Palatine, and Charles E. Lyon, lr., Des Plaines, Ill., assignors to Motorola, Inc., Chicago, Iii., a corporation of Iliinois Application .'luly 17, 1956, Serial No. 598,452 4 Claims. (Cl. 318-282) This invention relates generally to tuners for radio receivers and more particularly to signal seeking tuners of the motor driven type.

Various present day radio receivers use an electric motor for operation of the tuning mechanism to select stations. For example, some auto receivers incorporate a motor to scan the tuning range and include a control circuit to deenergize the motor automatically when a station is tuned. Thus, a driver of the auto can tune the receiver without unduly diverting his attention from driving. Obviously an automatic or signal seeking tuner should operate to scan a tuning range in both directions and should automatically reverse when the mechanism ias reached the end of its tuning range.

However, in providing a rugged and inexpensive automatic motor reversing device for a tuner, some difficulties may be experienced. For example, it is generally desired to make the receivers as compact as possible and any reversing mechanism for a drive motor must therefore fit into a small space. Furthermore, such a tuner device should work smoothly so as not to cause drag or friction on the drive motor. In addition, it may also be appreciated that in production techniques certain adjustments may have to be made among different receivers in order that operation of a motor reversing device takes place precisely at the desired setting of the tuner and therefore, a motor reversal device should be easily adjustable for proper operation in each particular receiver in which it is used.

Accordingly, it is an object of this invention to provide a reversal device for a signal seeker tuner motor which requires but little space in the tuner and which is of simple and sturdy construction,

Another object is to provide a motor reversing mechanism requiring a minimum of easily formed parts which operate smoothly to reduce drag on the tuner motor.

Another object is to provide signal seeking tuner apparatus which automatically reverses to scan back and forth across a frequency band and which is easily adjustable to permit setting the position at which scanning reversal takes place.

A feature of the invention is the provision of a small, thin, slidable actuating bracket mounted on the tuner frame and operative to trip a double pole double throw motor reversing switch.

Another feature is the provision of a slidable bracket having a tripping slot the sides of which are engageable by a guide lug portion of a reciprocating tuner carriage. The bracket is also operatively coupled to a snap action motor reversing switch.

A further feature of the invention is the provision of such a Switch actuating bracket including a pair of outward projections between which is disposed an operating arm of the tuner motor reversing switch. The projections include tool slots for adjustment thereof in the direction of bracket travel for setting the point of switch operation as related to the position of the tuner carriage.

Further object features and the attending advantages engaged in order to free .ffice if). l;

of the invention will be apparent upon consideration of the following description when taken in conjunction with the drawing, in which:

Fig. 1 is a top view of the essential mechanical components of a signal seeking tuner incorporating the invention;

Fig. 2 is a perspective View of a portion of the tuner of Fig. l; and

Fig. 3 is a schematic diagram of a radio receiver incorporating the invention.

T he invention comprises a motor reversing mechanism for signal seeking tuner apparatus. A carriage, slidable to adjust the frequency of a tuner, is supported by means of guide lugs in slots of an associated frame. A slidably mounted switch actuator bracket is disposed on the frame with a tripping slot thereof in registry with a slot of the frame. The tripping slot is shorter than the frame slot by a predetermined amount so that the carriage guide lug will engage and move the bracket at each extreme position of carriage travel. An operating arm of a double pole double throw motor reversing switch is positioned between two outward projections of the bracket to move the switch to different settings at the two extreme positions of the carrier. The motor is thus reversed at the proper time so that the tuner can scan and rescan its frequency range. The projections of the bracket are each slotted to receive a tool for bending these projections so that the tuner setting at which the switch is operated can be varied to t a particular tuner with a reversing device.

Fig. 1 shows a signal seeking tuner 10 which is of the type including push buttons operative to tune certain preferred stations. Inductance units 12, 13 and 14 each include respective timing slugs 16, 17 and 18 which are movable reciprocally within the inductance units for tuning purposes. The slugs are fastened to a reciprocating carriage 20 which is supported by means of guide lugs 26a and 201) in guide slots 22a and 23a, respectively, of frame members 22 and 23. Carriage 2,0 is linked t0 end members 25 and 26 between which extend parallel bars 27, 28 comprising a treadle. End members 25, 26 are pivotally mounted intermediate the rods 27, 28 in the frame members 22 and 23, respectively.

For manual operation of the tuner, shaft 30 may be rotated by a suitable knob (not shown) which turns gear 3l and drives pinion gear 33. This in turn operates crown gear 35, joined to pinion 36, which drives gear 38. Gear 38 is axed to a sleeve 40 Within which shaft 42 extends forming the rotational axis for end member 26. Sleeve 40 and shaft i2 are intercoupled by means of a clutch itso that rotation of gear 38 will also cause rotation of shaft 42 and rotation of treadle bars 27, 28. By thus positioning the treadle bars the carriage 20 may be moved, thereby tuning the induetance units 12-14.

It is also possible to adjust the tuning apparatus to certain predetermined frequencies by means of slidable push-button arms 48. Each of these arms carries a cam Sil having an edge disposed at a particular angle with respect to the direction of slidable movement of the associated arm. By sliding a push-button arm downwardly in Fig. l, a cam may be brought into engagement with the treadle bars 27, 28 to cause rotation of these bars about their pivotal axes thus sliding carriage 20 and tuning the inductance units 12-14.

When a push-button arm is operated, clutch 44 is disthe treadle bars from any retarding effect of the various gears used for other modes of driving the treadle bars. The push-button arms each carry a projection 52 which, upon slidable movement of an arm engage finger 54, one of which is associated with each projection 52, and all of which are carried by the clutch release arm 56. This arm is rotatable about an axle 58a so that rotation thereof moves cam 58 carried by the clutch release arm to bring this cam into engagement with lever 66 and pivot this lever in a counterclockwise direction about pivot 60a. Lever 60 includes a rounded cutout in the` top edge thereof (not shown) which is titted into an annular ring 38a of sleeve dit. Thus, when the clutch release arm 56 is rotated by a push button arm 48 the sleeve 40 is moved to the right in Fig. l to open clutch 44. Obviously, annular ring 33a ordinarily rides in engagement with lever 6i) making sleeve 40 freely rotatable.

For motor driven operation f the tuner, the applica.- tion of drivevpower to treadle bars 27, 28 is as follows: Motor 65 applies power through flexible S coupling 66 to the drive gear 68. Gear 68 drives planetary gear 69 which rotates with pinion gear 71. By means of suitable electrical circuitry not shown, solenoid 73 is also energized when motor 65 is energized which moves arm 73a into engagement with carrier gear 75 to prevent rotation thereof. gear 71 are held stationary about the axis of rotation of gear 63 and 75, so that gear 77 is driven by pinion 7l. Gear 77 is rotatable with gear 79 about the axis of rotation of gear 68 and gear 79 engages power gear 3l and causes rotation thereof. power gear 81 and both are mounted on the drive shaft 86. Gear 84 engages gear 31 which drives shaft 42 as previously described in connection with manual tuning7 that is, through gears 33, 35, 36, 33 and clutch 44.

At should also be pointed out that manual operation of shaft will cause rotation of drive shaft 86 through gears 31 and S4 which will rotate gears 81 and 79. However, during manual tuning, carrier gear 75 is free to turn and pinion gear 71 will remain stationary with respect to gear 77 so that planetary gear 69 will thus rotate about drive gear 68 which remains stationary. This construction tends to reduce the friction drag during manual tuning since a portion of the mechanism is not operated at such time.

It may be noted that upon operation of motor 65, the tuner carriage 20 will be operated in one of two directions depending upon the direction of rotation of the motor shaft and that the tuner will thus be scanned across its frequency range. As shown in Fig. 2 the apparatus includes a provision for automatically reversing the motor when the carriage has reached either end of its travel. A switch actuating bracket 9i) is disposed on the inner side of frame 23 and is slidably mounted in this position by means of rivets 92 afxed to the frame and engaging slots 93 in the bracket. An overturned lip 90a rides on top of the edge of frame 23. A tripping slot 95 in bracket 90 is in registry with slot 23a in which guide lug 2Gb rides. Tripping slot 95 is, however, of somewhat lesser length than slot 23a, so that this tripping lug will engage and slide the bracket 90 when the carriage reaches one of its maximum positions of travel.

A double pole double throw motor reversing switch 96 is also mounted on frame 23. This switch includes an operating arm 96a and stop members 9611. An insulating strip 97 joins the movable arms of the switch to the operating arm 96a and it is contemplated that the switch is of the snap action type. The one shown has movable contact arms which operate by an over center spring, so that when the switch is moved to either of its positions actuator arm 96a is moved in the direction of slidable travel of bracket 90 and insulator strip 97 is brought into engagement with either of switch stops 9617.

Switch actuating bracket 90 includes a pair of outward projections 99 which extend over the top edge of frame 23 in a. spaced manner so that switch actuating arm 96a is captured therebetween. Projections 99 include slots 99a therein into which a screwdriver may be inserted for the purpose of bending the projections in the direction of travel of bracket 90 in order to set the point at which the snap action of the switch will actually cause tripping Accordingly, the planetary gear 69 and pinion Pinion gear 34 is rotatable with and 104 in order to tune the receiver.

thereof. Thus, as carriage 2t? moves forward in the View of Fig. 2 the guide lug 2Gb thereof will engage the edge of tripping slot to slide bracket 9) forward and throw switch 96 to a different position, thus reversing the motor to drive the carriage in the opposite direction.

Fig. 3 illustrates the circuit to be used with tuning motor 65 when installed in a receiver of the signal seeking type. The receiver includes a radio frequency amplifier 102 which is coupled to antenna W3 and which applies si als to mixer-oscillator 164i. Circuit l'tii heterodynes a received signal and converts it to a signal of intermediate frequency after which it is applied to the intermediate frequency amplifier it and detected in demodulator 167. The resulting audio is then amplified in audio frequency amplifier N9 and applied to loudspeaker 1.19.

A control circuit i12 is shown coupled to the demodulator itl? and this circuit is constructed to deenergize relay 114 when a signal of predetermined strength is tuned by the receiver and further to maintain this relay energized, once it is in that condition, when such a signal is not yet tuned by the receiver. A switch M6 is coupied from one side of the relay to ground so that this switch may operated to initially energize the reiay for starting the automatic tuning operation. it may be seen that the reiay iid includes contacts :dan which short the speaker to silence the receiver during automatic tuning and contacts llib which ground a pair 0f fixed contacts of switch 96, which contacts are on opposite sides of the Contact arms of the switch. The remaining fixed contacts of swith 96 are connected to a positive potential source and the movable contact arms of this switch are coupled to the reversable electric motor 65. Accordingly, when contacts iid-b are closed, motor 65 will be energized to run in one direction with, for example, switch in the upper position and in the opposite direction with switch 96 in the downward position. As shown schematically in Fig. 3, the motor is mechanically coupled to carriage 20 and to inductance units i2, 13 and ist in circuits lil?. As previously explained when carriage E@ reaches the end or" its travel, for example, in the downward direction of' Fig. 3, bracket 9? will be engaged and moved downwardly to trip switch 96 and reverse the motor to cause upward travel of carriage 2S. Subsequently, sufficient upward travel will cause reversal of the apparatus again when carriage 20 reaches its maximum position in the opposite direction.

Accordingly, the invention provides reversing mechanism for a tuning motor which mechanism is of sturdy construction and requires but a minimum of space in the tuner. The tuner may be set into operation by manipulation of a single starting switch (switch 116) after which automatic tuning will continue until a station has been selected. At the ends of the frequency band when reversal of the tuner is necessary, that will be carried out automatically and without mechanically straining the apparatus such as may occur with some mechanical reversing device. lt may be noted that the switch actuating bracket may be of stamped construction and switch 96 may be formed of a plurality of insulating leaves interspersed with contact strips so that the components are of inexpensive construction. Fabrication expense is also reduced in that the bracket 96 includes provision for adjustment thereof to operate the switch in a desired manner thus simplifying original adjustment of a receiver.

We claim:

l. In a tuner for wave signals having a reversible electric motor to drive a carriage slidable between first and second positions of maximum travel which operates the tuner through a range of frequencies, the reversing mechanism for such tuner including in combination, frame means mounted transverse to the slidable carriage, a switch actuator siidably mounted on said frame means, said switch actuator having a first portion engaged by the carriage in the tirst position thereof to cause sliding movement of said actuator in one direction and a second portion spaced from said first portion and engageable by the carriage in the second position thereof to cause sliding movement of said actuator in the opposite direction, a double pole double throw switch supported on said frame means, said switch having an operating arm engaging said switch actuator so that said switch is operated on sliding movement of said actuator, and circuit means coupled to said switch and the electric motor to apply operating power thereto, said switch being coupled to the motor so that the same reverses retation when the switch is operated whereby the tuner may be driven back and forth through the tuning range thereof as the motor is controlled by said switch,

2. A tuner device for wave signals including in combination, an electric motor, variable means driven by said motor including a carriage adapted to move reciprocally for adjusting the tuner through a frequency range, frame means having slots therein, said carriage having projecting lugs disposed in said slots to guide the same during reciprocal movement, a switch actuator bracket slidably mounted on said frame means and having a slot in registry with a slot of said frame means so that a projecting lug of said carriage engages said bracket and causes slidable movement thereof at the ends of said frequency range, said bracket having a pair of closely spaced outward projections, `and a double pole double throw reversing switch coupled to said electric motor to control power applied thereto and the direction of rotation thereof, said switch including an Operating arm positioned between said projections to be operated by said bracket as the same is moved by said carriage for reversing said variable means.

3. A tuner device for wave signals including in combination, a reversible electric motor, variable tuning means including a carriage adapted to be moved reciprocally by said motor for scanning the tuner through a frequency range, frame means having slots therein for supporting said carriage, said carriage having projecting lugs disposed in said slots to guide the same during reciprocal movement, a switch actuator bracket slidably mounted on said frame means and having a tripping slot in registry with one slot of said frame means so that one of said projecting lugs engages said bracket and causes slidable movement thereof substantially at maximum positions of travel of said carriage, said actuator bracket having a pair of outward projections with slots therein to receive a tool for bending the same in the direction of slidable travel of said bracket, a snap action double pole double throw reversing switch coupled to the electric motor, power supply means, and circuit means coupling said power supply means through said switch to said motor so that said switch controls the direction of rotation thereof, said switch being disposed on said frame means and including an operating arm positioned between said outward projections to be operated by said bracket as the same is moved by said carriage for reversing said tuning means.

4. A tuner device for wave signals including in combination, a reversible electric motor, variable tuning means including a carriage adapted to be moved reciprocally by said motor for scanning the tuner through a frequency range, a frame for supporting said carriage during movement thereof, said carriage having a tripping portion in proximity with said frame which travels a predetermined distance as said tuning means scans between ends of said frequency range, a switch actuator bracket slidably mounted on said frame facing said carriage and having spaced portions aligned with said tripping portion and individually engageable therewith as said carriage approaches the ends of said tuning range whereby said bracket is slidably moved, said actuator bracket having a pair of closely spaced fingers projecting outwardly from said frame, a snap action double pole double throw reversing switch coupled to the electric motor, power supply means, and circuit means coupling said power supply means through said switch to said motor so that said switch controls the direction of rotation thereof, said switch being disposed on said frame and including an operating arm positioned between said spaced lingers to be operated by said bracket as the same is moved by said carriage for reversing said motor and the drive of said variable tuning means.

References Cited in the tile of this patent UNITED STATES PATENTS 2,616,066 Coleman Oct. 28, 1952 

